Canon 77mm Circular Polarising Filter

The product is slightly disappointing as I cannot put my lens cap on when it is fitted as it has no lip to allow this. I contacted the seller about this but they have given me no useful advice apart from telling me to contact Canon. I feel that they should be the ones contacting Canon about a product that costs this amount of money. Surely one should be able to put the lens cap on over a filter?

I've normally used specialist filter producers to provide UV and Circ polarisers and have not bothered with Canon's own. Due to a quirk of fate I just bought one of the Canon 77mm circ polarisers and was amazed at the result. The quality of the product and the colour rendition it provides are streaks ahead of anything I have used before (costing as much or more). Absolutely super polariser. I shall be bying Canon filters from now on regardless of cost, worth every penny.